For decades, breast cancer was considered a single disease. Recent research, however, suggested it was a number of genetically distinct variations—and now a new study has split the disease into four differently treatable types.

For years, we've been treating breast cancer as a single disease. But a new study has…
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The study, published yesterday in Nature, is the first comprehensive genetic analysis of breast cancer to date. It suggests that four distinct types of the cancer display hallmark genetic changes, that in the future will be targeted by different treatments.

Part of a project called the Cancer Genome Atlas, designed to build comprehensive maps of genetic changes in common cancers, the study included analysis of tumors from 825 patients. While the researchers found at least 40 genetic alterations that might be attacked by drugs, four of the genetic effects are fundamentally different between the four identified cancer types. Joe Gray, a genetic expert at Oregon Health & Science University, told the New York Times:

"We now have a good view of what goes wrong in breast cancer. We haven't had that before."

Amazingly, the finding offers some immediate implications. The results suggest that routine treatments often used in ovarian cancer could instead be applied to some breast cancers. As ever, though, it's best not to get too over-excited by the finding: while ground-breaking, the finding acts as more of a starting point.

Indeed, the researchers are keen to point out that it will take years to translate some of the new findings into safe, targeted treatments, especially given that individual cancerous tumors of the same type can vary so much case-to-case. But in the longer term, the finding opens up the possibility of diagnosis made on the back of genetic analysis, and tailored treatments plans of drugs and other therapies. The sooner, the better. [Nature via New York Times]